Eu- and AF-labeled protein L titration assays.

<p>AF-labeled protein L was titrated (100–6.3 nM) separately with <b>A</b>) Eu-labeled GST-VP1u and <b>B</b>) Eu-labeled SA. Eu-labeled protein L was titrated (100–6.3 nM) separately with <b>C</b>) AF-labeled SA and <b>D</b>) AF-labeled GST-VP1u. The anti-GST antibody was used as control for SA and anti-SA antibody for GST-VP1u. The third line represents a background control without antibody. The y-axis represents response counts obtained from Victor fluorometer. The error bars represent ± standard deviation between parallel wells.